U.S. Pat. No. 5,904,734, to S.C. Johnson, discloses bleaching systems that contain a peroxide and an activator. The activator is a tungsten containing compound, preferred compounds are sodium tungstate or tungstosilicic acid.
U.S. Pat. No. 5,041,142, to lever Bothers, bleaching compositions comprising monomer molybdenum or tungsten derived peroxymetallate bleach activators. The compositions are disclosed as comprising from about 1 to 60% of a peroxygen compound capable of yielding hydrogen peroxide.
U.S. Pat. No. 6,074,437, to Unilever, discloses a bleaching composition incorporating polyoxometalates and being free of any effective amount of a bleaching agent such as hydrogen peroxide, organic peracids, inorganic peracids, organic persalts, and inorganic persalts. Air is employed as a primary source of oxygen atoms for bleaching.